Electronic vacuum tube



March 5, 1957 J. KATES ELECTRONIC VACUUM TUBE 9 Sheets-Sheet 2 Filed Jan. 17, 1951 JVENTOR 17585; I64Ts March 5, 1957 J KATEs 2,784,312

ELECTRONIC VACUUM TUBE Filed Jan. 17, 1951 9 Sheets-Sheet 4 MUL T/PL/CAND. o

PART/AL PPODUCTo- B/NARY CARRY /VUL77PL/E -O PAP T/AL PIPODUC T -0 CA PPY JVENTOP dbs r KATES JBY- March 5, 1957 J. KATES ELECTRONIC VACUUM TUBE Filed Jan. 17, 1951 9 Sheets-Sheet 5 J/T/l/ENTOA T708127 KATES .BYW..

March 5, 1957 J. KATES 2,784,312

ELECTRONIC VACUUM TUBE Filed Jan. 17, 1951 9 Sheets-Sheet a BY-WW ATTYS.

March 1957 J. KATES 2,784,312

ELECTRONIC VACUUM TUBE Filed Jan. 17, 1951 9 She ets-Sheet 7 ATTYS- March 5, 1957 J. KATES' 2,784,312

ELECTRONIC VACUUM TUBE Filed Jan. 17, 1951 9 Sheets-Sheet 8 2,784,312 Patented Mar. 5, 1957 United States Patent Office ELECTRONIC VACUUM TUBE Josef Kates, Toronto, Ontario, Canada, assignor to National Research Council, Ottawa, Ontario, Canada, a body corporate of Canada Application January 17, 1951, Serial No. 206,394

Claims priority, application Great Britain February 8, 1950 13 Claims. (Cl. 250-27) The invention relates to an electronic vacuum tube having characteristics making it adapted to perform the functions indicated by a function table, for example, the function table for addition, for subtraction, for multiplication, for division, or for a switching arrangement in which control of the individual selection of more load circuits than there are control circuits may be effected.

Although the invention is applicable to any system of notation, it will be described as applied to the binary system of notation because of that systems arithmetic simplicity and the ease with which binary numbers can be represented in a physical system. The binary system, like the decimal system, is one particular system of a class of notations referred to as the general system of notation.

. Electronic computor circuits are known which will fulfil the functions of a given function table but they have had limited application since, even for the simpler types of binary function tables such as the one given above, the circuits become very complicated for computers having a high speed of operation. For example, one stage of a known type of electronic binary adder adapted to per form the functions indicated by the function table for binary addition would require at least five conventional amplifier tubes and twenty diode tubes with associated circuitry.

According to the present invention there is provided an electronic vacuum tube which is effective, ina circuit according to the present invention, as physical embodiments of a particular type of function table so that, if the tube has simultaneously applied to it a set of input voltages corresponding to a particular set of input numerals in the function table, the tube will produce output voltages corresponding to the set of output numerals associated with that particular set of input numerals in the function table.

An electronic vacuum tube according to the present invention is one having an electron emissive cathode, a plurality of input electrodes to which one of two discrete input potentials can be applied individually and selectively, each combination of said input potentials on the input electrodes resulting in a unique characteristic potential distribution in the region between the input electrodes and the cathode, the direction of the maximum potential gradient for each said characteristic potential distribution determining the direction of electron flow, and at least one output electrode to be maintained at a positive potential with respect to the cathode and located as a target for elecrons flowing in a unique direction as determined by a said maximum potential gradient, the electrons flowing to said target being confined as a beam due atleast partly to current limiting means in the external cathode or input electrode circuits of the tube.

A preferred arrangement has a cylindrical cathode with the input and output electrodes shaped as sections of the surfaces of cylinders or conoids concentric with the oath: ode.

In another preferred arrangement each input electrode,

comprises a plurality of component electrodes, each combination of the input potentials on said component electrodes resulting in a plurality of unique characteristic potential distributions in the region between said component electrodes and the cathode, whereby for each combination of input'potentials a plurality of electron beams are directed to one output electrode.

A tube according to the invention can be of the receiving (miniature) tube size having, for example, a central cylindrical cathode about which are concentrically arranged input and output electrodes which are shaped as sections of the surfaces of cylinders or conoids. There is one input electrode corresponding to each input channel, and one output electrode corresponding to each output channel. In operation, a given combination of input potentials results in beamed current flow in a given direction or given directions to a corresponding com bination of output electrodes. Series resistors or other current limiting means, for example a vacuum tube, in either the cathode or input circuits restrict the spread of the electron beam or beams to a suitable width; The function of the series resistors is to adjust the ratio of positive and negative potentials on the input electrodes with respect to the cathode which results in control of the width of the beam or beams of electrons. Each output electrode is placed-so as to intersect the maximum potential gradient for its corresponding combination of input potentials on the input electrodes.

Other preferred arrangements of the present invention will be described below in connection with explanation of use of tubes according'to the invention to fulfil the requirement-s of various function tables. 7

A tube according to the invention, when used with current limiting means as mentioned above, may be made effective as a physical embodiment of a binary function table for the computation to be performed. For example, in the case of addition the binary. function table requires that there be three inputs, one for' the carry numeral, one for the addend numeral "and one for the augend numeral, and that there be two output terminals, one for the sum numeral and one for the carry numeral to the next stage. According to the binary function table for addition there may be eight (2 different arrangements of the carry, addend and augend input 'numerals. For the eight dilferent arrangements'of the input numerals there are four different arrangements of the sum and carry output numerals. The numerals in the binary function table may be represented by voltages, the O numeral being represented by a negative voltage and the 1 numeral being represented by a positive voltage, or vice versa. A tube according to the invention which fulfils the requirementso-f the binary function table for addition has, in a preferred form of the tube, a central electron emissive cathode surrounded by'three input control electrodes each being in the form of a' section of a cylinder which is coaxial with the cathode which may be of the usual cylindrical type. Each input electrode has at least one opening, and two output electrodes are coaxially arranged about the outside of the'input electrodes. The carry output electrode has a fin extending across each space between the input electrodes and radially in line with the cathode, and the sum output electrode has a fin extending across the central part of each input electrode and radially in line with the cathode. Further, there may be an electrode between the input electrodes and output electrodes to serve in the usual manner as a screen grid. With such an arrangement, when all the input electrodes are negative with respect to the cathode, as is the case when all the input numerals in a horizontal line of the binary function table are 0, and 0 is represented by a negative input voltage, no electrons are transmitted from the cathode to the output electrodes. When one of the input electrodes is positive with respect to the cathode and the other two input electrodes are negative, as is the case when the input carry is 1 while the addend and a'ugend are each Q, the electrons emitted from the cathode will be directed to the positive input electrode and will pass through an opening in its central area to a fin of the sum output electrode. Since the sum for the combination of input elements of 1, and O is 1, collection of electron current by the sum output electrode is taken to represent 1. If two of the input electrodes are positive while the other is negative, as is the case when the carry and the addend are 1 while the augend is 0, the electrons emitted from the cathode will be directed between the two positive input electrodes to the output carry electrode. Current to the carry input electrode represents a carry of l and absence of current to the sum electrode represents a sum of 0 which agrees with the output elements shown in the binary function table for addition in the case in which the input carry and addend are l and the augend is 0. When all three input electrodes have positive voltages supplied to them, as is the case when the addend, augend and carry are each 1, six electro'nstreams will flow from the cathode, one through each of the input electrodes, and one stream, through each space between the input electrodes. In this case, the sum and carry electrodes will each receive current indicating that the sum is 1 and the carry to the next stage is also 1, which agrees with the binary'function table for addition.

The current limiting means used with an electronic vacuum tube according to the present invention stabilizes the tube. If the current limiting means has a resistance 'which is large compared to the equivalent resistance of the tube, the input voltages to the tube may be allowed to vary over a wide range since the electron beam formingproperty of the tube depends on the ratio between the positive and negative input voltages with respect to cathode voltage. If the current limiting means is a re- 'sistance in the cathode circuit, thevvoltage drop across the resistance, caused by the current flow due to electrons leaving the cathode, adjusts the cathode voltage keeping its ratio to the voltage of each of the input electrodes in the proper range. ,HoWever, resistances in the input electrode circuitswill serve the same purpose since electron fiow to the input electrodes would then cause an adjustment'of their voltages with respect to that of the cathode.

Inv this specification the meaning of the term large as applied to the resistance value of the current limiting means is that, if the current limiting means were to be short circuited, a relatively large current increase would result but, if the tube were short circuited, only a small current in crease would result.

In a tube accordingtothe invention, as illustrated by the above description of the operationof a binary adder tube, electron flow is along the line of maximum potential gradient established among a plurality of input electrodes by their voltages, their shape and their positions relative to one another. By use of current limiting means having a large value of resistance, the electron paths are limited to a relatively narrow region around the line of maximum potential gradient. Deflection of theelectron beam, or beams, is effected by changing the voltage of one or more of the input electrodes. In general, a tube having 21 input electrodeseach of which can be at one of m discrete voltages will have m distinct maximum potential gradients and, therefore, m", distinct electron paths. The outputelectrodes are located so that when a given combination of voltages on the input electrodes exists, a predetermined output electrode receives current.

A tube according to the invention, when arranged for operation in a cell of a binary multiplier, hasfour input electrodes and two output electrodes since thebinary function table for multiplication shows that four input elements of information are used to compute the product which is indicated in the form of two output elements, namely, the partial product and the carry. The input elements are the multiplier, the multiplicand, the partial product and the carry, the later two elements being supplied from a previous stage. The partial product and carry input electrodes of the tube .are in the form of sections of a cylinder having its centre at the cathode and each section having a central opening. The multiplier and multiplicand input electrodes are also in forms of sections of a cylinder having its centre at the cathode and having the same radius as the other input electrodes. The multiplier and multiplicand electrodes are spaced apart in the same direction as that of the axis of the oathode. The partial product, ca l'y, multiplier and multiplicand input electrodes are all arranged cylindrically about the cathode. The partial product output electrode consists of three fins electrically connected together and having a fin outside of each central opening of the partial product and carry input electrodes while its third fin is outside the space between the multiplier and the multiplicand input electrodes. The carry output electrode is in the form of a single fin outside the space between the partial product and the carry input electrodes, and has a ring extending centrally around the outside of thepartial product and carry input electrodes and around the outside of the space between the multiplier and multiplicaud electrodes.

As explained above the digits of the binary system, 0 and 1, may be represented by a negative and positive voltage respectively, or vice versa, resulting from the absence or presence of current to an output electrode of the tube. By the term absence of current is meant current below'a given level A and by the term presence of current is meantcurren't above a given level B where B A. Tubes according to the invention when used in a multiple cell binary adder may be arranged so that 0 and 1 are represented by the same polarities at the input and output of each-cel lor the polarity representing each digit may be reversed at the input of each successive cell. If, in a tube according to the invention, it is desired that current to an outpiit electrode should result in a positive output voltage, the output electrodes may be formed from material having a secondary emission coeflicient greater than 1, and a collector electrode may be placed between the input-electrodes and the output electrodes. The collector would have openings to allow the streams of electrons formed in the tube to reach the output electrodes and would,"in operation, be'kept at apositive volt-- age higher than that of the output'electrodes. In operation, the collector electrode would receive more electrons from the output electrodes than they receive from the cathode with the result that a stream of electrons to an output electrode would cause that electrode to rise in voltage to approximately that of the collectorelectro'de.

The inventionwill be further described by reference to the attached drawings, which illustrate certain embodiments of it and in which:

Figure l is a block diagram of a single cell'bina'ryadder,

Figure 2 is a block type diagram of a 'mul tiple'cell binary adder,

Figure 3 is an explodedisometric view of a binary adder tube according to the invention,

Figure 4 is a diagrammatic end view of the electrode structure of the binary adder tube shown in Figure 3,

Figures 5 to 8 inclusive are diagrammatic end views similar to Figure 4 and showing the different states of conduction which may occur in thetube' during binary addition,

Figure 9 is a schematic diagram of three cells of a binary adder usingtu'bes according tothe present invention and corresponding to the block diagram of Figure 2,

Figure l0is an exploded isometric view of a binary subtractor tube according to the invention,

Figure 11 is a diagrammatic end view of the tube shown in Figure 10,

Figure 12 is an exploded isometric view of a binary adder-subtractor tube 'according'to the invention,

Figure 13 is a diagrammatic end view of the tube shown in Figure 12,

Figure 14 is an exploded isometric view of a binary multiplier tube according to the invention,

Figure 15 is a block diagram of a single cell of a binary multiplier in which a tube as shown in Figure 14 may be used,

Figure 16 is an exploded isometric view of a singlepole double-throw switch tube according to the invention,

Figure 17 is a diagrammatic end view of the tube shown in Figure 1,

V Figure 18 is an exploded isometric view of a 3 x 8 matrix tube according to the invention,

Figure 19 is a schematic diagram showing typical circuit connections for a 3 x 8 matrix tube as shown in Figure 18,

Figure 20 is an exploded isometric view of a binary adder tube arranged for double electron beams, according to the invention,

' Figure 21 is a diagrammatic end view of the electrode structure of the binary adder tube shown in Figure 20,

Figures 22, 23 and 24 are diagrammatic end views similar to Figure 21 and showing different states of conduction which may occur in the tube during binary addition,

Figure 25 is an exploded isometric view of a binary adder tube arranged for four electron beam operation,

according to the invention,

Figure 26 is a diagrammatic end view of the electrode structure of the binary adder tube shown in Figure 25, and

Figures 27, 28 and 29 are diagrammatic end veiws similar to Figure 26 and showing difierent states of conduction which may occur in the tube during binary addition.

A single cell of a binary adder is shown in block form in Figure 1. As shown a single cell has three input connections, one for the carry from the previous cell, one for the addend, and one for the augend. Since addition of the carry, addend and augend results in a sum and a carry to the next cell, a single cell has two output connections, one for the sum an one for the carry to the next cell.

In Figure 2 there is shown an example of binary (scale of 2) addition as well as addition of the same numbers in the decimal system (scale of 10). The decimal system number 5 is written 101 in the binary system and the decimal system number 7 is written 111 in the binary system. Addition of the binary numbers is performed as follows:

First column (from the right): 1 and 1 gives the sum with 1 to carry,

Second column: 1, 0 and 1 gives the sum 0 with 1 to Third column: 1, 1 and 1 gives the sum 1 with 1 to carry, and the 1 to carry becomes the fourth numeral to the left of the sum of the two binary numbers.

The sum 1100 is the binary equivalent of 12 in the scale of 10.

A binary adder having tubes according to the invention requires one tube for each vertical row of numerals to be added and, for the example given in Figure 2, three tubes are required making the adder a three cell one as shown in the block diagram of Figure 2. In the block diagram, the three cells are designated by the numbers 10, 11 and 12 and, at'the input and output of each cell, the digits 0 and 1 are represented respectively by a negative and positive voltage. Each cell has three input circuits, one for the carry from the previous stage, one for the addend and one for the augend, and each cell has two output circuits, one for the carry to the next cell and one for the sum. As shown in Figure 2, the 1st cell which adds the numerals in the first column from the right has its carry input connection connected to a source of negative potential since there is no carry tothis cell. The addend input circuit of the 1st cell connects to a source of voltage which supplies a voltage indicative of the addend"- Since the binary system l+l=0, the sum output circuit- 17 of the 1st cell supplies a negative voltage indicative of the numeral 0. Since in the case of 1+1 there is 1 to carry, the carry output circuit 18 supplies a positive voltage to the carry input circuit 27 of the 2nd cell 11. In the case of the 2nd cell, the input voltages appliedto the addend input circuit 19 and the augend input circuit are negative and positive respectively since the addend and augend in the second column from the right are 0 and 1 respectively. A carry of 1 is supplied to the 2nd cell and it must add 1, Oand 1 which gives a sum of 0 with a carry of 1 into the next cell. The sum of 0 is indicated by a negative voltage supplied-by the sum output circuit 21, and the carry of 1 to the 3rd cell is transferred to its carry input circuit 28 as a positive voltage by the carry output connection 22 of the 2nd cell. The addend and augend input circuits 23 and 24 of the 3rd cell are each positive since the addend and augend in the 3rd column from the right of the example of binary addition are each 1, and the sum and carry output connectionsand 26 of the 3rd cell are each positive, indicating that the sum and carry are eachl. The carry oil from the 3rd cell becomes the numeral appearing'at the; left hand side of the complete sum of the two binary; numbers. The polarities of the carry output circuit 26; and of the output circuits 25, 21 and 17 will be respecing 39, 40 and 41 respectively. The central openings 39, 40 and 41 are rectangular in shape, each having its longer sides parallel to the axis of the cathode 35. The input electrodes 36, 37 and 38 are cylindrically arranged about the cathode with a space 42 between the input electrodes 36 and 37, a space 43 between the inputf'electrodes 37 and 38 and a space 44 between the input electrodes 38 and 36. A collector electrode '65 in the form of a cylinder fits coaxially about the input electrodes 36, 37 and 38 and the cathode 35. The collector electrode 65 has elongated rectangular openings 45, 46, 47, 48, 49 and 50. The openings 45 to 50 are of the same size and shape as the openings 39, and 41 in the input electrodes 36, 37 and 38. The opening is located outside of the opening 39 so that an'electron stream from the cathode 35 can pass in a straight line through the openings 39 and 48. Similarly, the openings 46, 47, 48,

49 and 50 are respectively outside the space 42, theopening 40, the space 43, the opening 41 and the space 44. As shown an output electrode 51 fits coaxially over the collecting electrode 65 and has three fins 52, 53 and 54 which extend the length of the collecting electrode 65 and which are arranged to be radially in line with the spaces 42, 43 and 44 between the input electrodes 36, 37 and 38. Another output electrode 55 of the same diameter as the output electrode 51 has three fins 56, 57 and 58 extending in the opposite direction to those of the output electrode 51. The fins 56, 57 and 58 are arranged to lie outside the openings 39, 40 and. 41 in the input electrodes 36, 37 and 38.

As an example, a binary'adder tube as shown in Fig The augend input circuit 16 of enamels 3. and 4 may have a in pin minature Stemwi h a 63 volt, mp re heater nd a s and d gl ss bulb d amete s o th elec de y be pp o m y as'follows:

Cethode 0.025 inch (0.635 millimeter) Input electrodes 0.250 inch (6.350 millimeters) Collector electrode, 0.400 inch (10.160 millimeters) Sum and carry output electrodes r, 0.600 inch (15.240 millimeters) The voltages applied to the sum and carry output electrodes may he 200 volts and the cathode resistor may have a value in the range from one-half megohm to 3 megohms. The voltages applied to the input electrodes maybe, for example, 457 volts negative and 150 volts positive.

The operation of the binary adder tube shown in Figures", 3' and 4 is diagrammatically illustrated in Figures 5, to 8 inclusive, and the circuit connections for the tube are schematically shown in Figure 9. In Figures to 8, the collector electrode 65' is not shown since it is not required for an explanation of the general operation of the tube and its function will be discussed below. In Figure 5, a negative voltage is applied to each of the input electrodes 36, 37" and 38 corresponding to the case in binary addition in which the carry, addend and augend are each 0. Witha' negative voltage on each of the electrodes 36, 37 and 38, the potential gradient established about the cathode 3S prevents the cathode 35 from emitting electrons which can reach the output electrodes 51 and 55 and consequently there are no streams of electrons shown flowing to the fins of the output electrodes 51 and 55. Operation of the binary adder tube as shown in Figure 5 corresponds to the-following section of the binary func- In Figure 6, the input electrode 36 is at a positive voltage, while the input electrodes 37 and 38 are at negative voltages. This is an arrangement of voltages of the input electrodes which corresponds to the case in binary addition. in which the carry is. l and the addend and augcnd, are each, 0. The potential gradient established within the tube by the voltages of the input electrodes 36, 37' and 38 causea stream of electrons 59 to be directed throughzthe central opening 39 in the positive input electrode;36. to tbefiu S6 of the. output electrode 55 which is maintained; at a higher positive voltage than that of input electrode; 36,. As will be explained below, a stream of electrons impinging on anroutput electrode causes its outputcircuit toproducc a positive voltage which is the voltage'corresponding to the binary numeral 1. Reference back to'thefunctiontablesfor binary addition will confirm that the operation; of'th-c tube as shown by Figure 6 corresponds, to the: following section of the binary function table:

Input Output Garry Addend Augend Sum Carry 1 0 0 0 l 0' l 0 l1 0 1 It is to be noted that, while theabove description of, the operation ofithe tubems shownby Eigure Gisdirected to the casein which input electrode 36 is positive, in other cas'es it may be electrode 37 or 38 which is positive,

and that for a positive voltage on any one input electrode, there will be formed a single stream of electrons to one of the fins 56, 57 or 58 of the output electrode 55, while there will be no electronstream formed to any of the fins 52, 53 or 54 of the output electrode 51, so that the output electrode 51 has a negative voltage relative to the output electrode 55. trode 55 represents the binary sum numeral 1, and the negative voltage of the output electrode 51 reprsents the binary carry numeral 0.

Figure 7 illustrates the case in which the input electrodes 36 and 37 are each positive, while the input electrode 38 is negative. This is an arrangement of the potentials of the input electrodes for the case in which the carry and add end are each 1 and the augend is 0. Under these conditions, the potential gradient formed about the oathode 35 causes a stream of electrons to be formed and directed to the fin 52 of the output electrode 51. The output electrode is made positive by the stream of electrons 60 and, since the voltage of the output electrode 55 remains unchanged, the output electrode 55 is negative with respect to the output electrode 51. The voltages of the output electrodes 55 and 51 correspond to a sum of 0 and a carry of 1. Operation of the tube in accordance with Figure 7 corresponds to the following section of the binary function table for addition:

Input Output Carry Add- Aug- Sum Carry end end As shown in Figure 8, each of the input electrodes 36, 37 and 38 has a positive voltage applied to it and the potential. gradient established in the tube causes six electron streams 59, 60, 61, 62, 63 and 64 to be formed and directed respectively to the fins 56, 52, 57, 53' and 58 and 54 of the output electrodes 51 and 55. The electron streams form a positive voltage on each of the output electrodes 51 and 55 corresponding to an output sumof l and carry of 1. Theoperation of the binary adder tube as shown in Figure 8 corresponds to the following section of the binary function table for addition:

Input Output;

Carry Add- Aug- Sum Carry end end Figure 9 is a schematic drawing corresponding to the block diagram shown in Figure 2 and in each cell there is shown aschematic representation of a binary adder tube, '70, 71 and 72, according to the invention. The cells n, n+1 'andn-l-Z in Figure 9 correspond to-the lst, 2nd and 3rd cells in Figure 2, and the electrodes of the tubes 70; 71, and 72 are each given the samedesignation as those of the tubes shown in Figures 3 to 8 inclusive-L Since the output-electrodes 51 and 55 are heldat high enough positive voltage to attract electrons emitted by the cathode 35, they are shown by the same symbol as used for a plate in a conventional tube. The collector electrode is also held at a positive voltage and since it has openings through which the electrons pass, it is shown by the same symbol as for a conventional screen grid.

The input electrodes 36, 37 and 38' control the flow. of; electrons from. the cathode: t0 the output electrodes- 5 and 55 and therefore they are shown by the conventional The positive voltage of the output elec-- symbols for control grids. In the schematic drawing the tube 70 is the one which adds the nth vertical row from the right of numerals in binary addition, and which for the example given in Figure 2 is the right hand row. Numerals in the second row from the right will be designated as (n+1) and the third row as (n+2). A resistor 73 is connected from the cathode 35 of each of the tubes 70, 71 and 72 to ground. A resistor 74 connects to each of the input electrodes 36, 37 and 38, and in the case of input electrodes 36 and 37 the resistors 74 connect to addend and augend input circuits 75 and 76. Each of the output electrodes 51 and 55 is connected by a resistor 77 to a source of positive voltage 78. Each collector electrode 65 is directly connected to a source 79 of higher positive voltage than the source 73. From each output electrode 55 there is a connection 80 to a resistor 81 which is in series with another resistor 82 and a source 84 of negative voltage. The input electrode 38 is connected to the common connection 86 between the resistors 81 and 82 by a resistor 74. In operation the resistors 73 stabilize the tubes and control their beam forming properties. The resistors 74 serve to smooth out variations in the voltages applied to the input electrodes 36, 37 and 38, and the resistors 77 in the plate circuits of the tubes serve as plate loads in the usual manner. The resistors 81 and 82 act as voltage dividers to provide a suitable operating voltage for the input electrodes 38.

A binary subtractor tube according to the invention is shown in Figures 10 and 11. The cathode 90 and the input electrodes 91, 92 and 93 with central rectangular Openings 96, 97 and 98 are the same in construction and arrangement as the cathode and input electrodes of the binary adder tube described above. The input electrodes 91, 92 and 93 are respectively the minuend input, the subtrahend input and the carry input. In the binary subtractor tube there are two output electrodes 94 and 95 being respectively the difference output and the carry output. The difference output electrode 94 has three fins 99, 100 and 101 arranged to collect the current (part of the current in the case of the short fins 100 and 101) which passes through the openings 96, 97 and 98 of the input electrodes 91, 92 and 93. The carry output electrode is arranged to collect part of the current which passes through the openings 97 and 98 of the subtrahend and carry input electrodes 92 and 93 and also the current passing through the space 102 between these two input electrodes. The binary subtractor tube is capable of carrying out the functions indicated by the following function table for binary subtraction and, in principle, the operation of the binary subtractor tube is similar to that of the binary adder tube described above.

Function table for binary subtraction Input Output Carry subtrahend Minnend Difierence Carry 1 0 0 O 1 0 l 1 1 1 l A tube construction according to the invention and providing the combined functions of the binary adder tube and the binary subtractor tube is shown in Figures l2 and 13. This tube,-which will be referred to as a binary adder-subtractor tube, comprises a central cathode 105, which may be in two sections 106 and 107,

input electrodes 108, 109 and 110 of the same construe tion and arrangement as the input electrodes of either of the binary adder or binary subtractor tubes, a sum-dif-' ference output electrode 111 and a carry output electrode 112. The input electrodes 108, 109 and 110 have cen tral rectangular openings 113, 114 and 115 and are separated from each other by spaces 116, 117 and 118; The sum-difference output electrode 111 has three fins 119, 120 and 121 arranged respectively to collect the current (part of the current in the case of short fins 120 and 121) which pases through the openings 113, 114 and 115 in the input electrodes. The carry output electrode has three fins 122, 123 and 124 arranged respectively to collect the current which passes through the spaces 116, 117 and 118 between the input electrodes. The carry output electrode 112 also extends across part of the openings 114 and 115 in the input electrodes 109 and 110. In addition, gating electrodes 125, 126, 127 and 128 may be included in the tube, in which case the cathode 105 would be in a single section. Gating elec-' trodes and 126 extend between the input electrodes and the output electrodes and have screened openings 129- and 130 aligned radially of the tube with the spaces 116 and 118. Gating electrodes 127 and 128 also extend between the input and the output electrodes and have screened openings 131 and 132 aligned radially of the tube with the openings 114 and 115 in the input electrodes 109 and 110. However, the gating electrodes 127 and 128 extend across only the parts of the openings 114 and 115 which are radially aligned with the carry output electrode 112.

The operation of the binary adder-subtractor tube as either an adder or a subtractor depends on whether the upper 01' lower part of the tube is used. If a two section cathode is used, the mode of operation depends on which cathode is energized, but if a single cathode and the gating electrodes are used, the mode of operation depends on the voltages applied to the gating electrodes. With the gating electrodes 125 and 126 negative and the gating electrodes 127 and 128 positive, the tube will act as a subtractor and with the voltages of the gating elec trodes reversed the tube will act as an adder. A negative voltage on both sets of gating electrodes will cause the tube to be shut off entirely.

In Figure 14 there is shown a binary multiplier tube constructed according to the invention to operate as a single cell of a binary multiplier as shown in Figure 15 A single cell of a binary multiplier has a multiplier input, a multiplicand input, a partial product input and a carry from the previous cell input. The output connections of the cell are a partial product output and a carry to the next cell output.

As shown in Figure 14, a binary multiplier tube according to the invention comprises a central cathode 140,

a set of four input electrodes consisting of the partial; product and carry input electrodes 141 and 142 and the multiplier and multiplicand input electrodes 143. and 144. Electrodes 141 and 142 have openings 145' and 146 respectively and are spaced apart by a space 147. Electrodes 143 and 144 do not have any openings and are spaced apart in the direction of the axis of the cathode by a space 148. The partial product output electrode 149 has three fins 150, 151 and 152 arranged to collect current which passes through the openings 145, (and 146 and the space 148. The: carry output electrode 153 has a single fin 154 arranged to collect the current or the region between the electrodes 141, 143 and 144 in 11 the case in which both electrodes 143 and 144 are positive as well as one or both of the electrodes 141 and 142. The general principles of operation are the same as for the binary ladder tube described above, but the binary multiplier tube fulfills the functions required by the binary multiplication table, for a single cell binary multiplier, as given below.

Single cell binary multiplier function table Input Output Multiplier Multiplicand Partial Carry Partial Carry I Product Product l 1 O 0 O 0 l O 0 0 0 1 l 0 l 0 1 O 0 1 l 0 1 0 0 1 0 1 0 1 l 1 1 0 g l 1 O l 0 0 l 1 0 1 l O 1 1 0 1 l 1 Tubes may be constructed and used according to the invention for many other purposes than the ones described in detail above. For example, a tube according to the invention may function as a single-pole double-throw switch, acell for a binary divider, a 3 x 8 matrix (three input circuits-eight output circuits) switch tube, etc., when used in a circuit including current limiting means for controlling the electron beam forming properties of the tube by controlling the ratio between the positive and the negative input voltages with respect to the cathode voltage.

Figures 16 and 17 illustrate a preferred form of a single-pole double-throw switch tube in accordance with the invention in which three input electrodes 210, 211 and 212 are concentrically arranged about a central cylindrical cathode 213. The input electrodes 210, 211 and 212 respectively have central elongated openings 214, 215 and 216. As. shown, there are openings 217, 218 and 219 between adjacent edges of the input electrodes 210, 211 and 212. A cylindrical output electrode 220 is concentrically arranged about the outside of the input electrodes 210, 211 and 212, and has a wide fin 221 extending the length of the input electrodes 210, 211 and 212. The fin 221 extends in width past the input electrode 210 and the opening 217. The output electrode 220 also has a narrow fin 222 extending the length of the input electrodes 210, 211 and 212 and, in width, extending across the opening 218 between the input electrodes 211 and 212.

With the arrangement of the input and output electrodes shown in Figures 16 and 17, input electrode 210 is one input, while input electrode 211 is the second input and input electrode 212 is the switch input. The presence or obsence of current to the output electrode 220 is determined by the potential of one of the two input electrodes 210 and 211, depending on the potential of the switch input electrode 212. In general, the voltages to be applied to the electrodes, and the manner "of applying them, including the use of current limiting means to provide focussing of the electron flow from the cathode are the some as described above for other types of tubes in accordance with the invention.

, A 3 x 8 matrix switch tube according to the invention is shown in .Figure 18. As shown in :the figure, the

electrodes are concentrically arranged about a cathode cathode 225 is a ring-shaped deflecting electrode 226 having .a series of rectangular openings 227. Above the deflecting electrode 226 are three input electrodes 228, 229 and 230 respectively in the shape of sections of the surfaces of conoids and having central conic openings 231, 232 and 233. Between the adjacent edges of the input electrodes 228, 229 and 230 are spaces 234, 235 and 236. A secondary electron collector 237 sits over the input electrodes 228, 229 and 230 and the deflecting electrode 226 "having a series of rectangular openings 238 corresponding to the rectangular openings 227 in the deflecting electrode 226, and a series of conic openings 239 corresponding to the openings 231, 232 and 233 in the input electrodes 228, 229 and 230 and to the spaccs 234, 235 and 236 between the input electrodes 228, 229 and 230. The secondary electron collector 237 is conic and has an axial opening 240 above the tip of the cathode 225.

As shown in Figure 18, a set of eight output electrodes 241, 242, 243, 244, 245, 246, 247 and 243 are arranged about the outside of the secondary electron collector 237. The ring-shaped output electrode 241 encircles the deflecting electrode 226 and the output electrodes 242 to 247 inclusive are respectively arranged outside the opening 231, the space 234, the opening 232, the space 235, the opening 233, and the space 236. The disc-shaped output electrode 248 is arranged above the opening 240 in the secondary electron collector 237.

As an example, a 3 x 8 matrix tube, according to the invention and as shown in Figure 18, is shown schematically in the circuit of Figure 19. In Figure 19 the conventional plate symbol has been used to represent each of the output electrodes 241 to 248 inclusive, and the conventional grid symbol has been used 'to represent each of the input electrodes 228, 229 and 230 and the secondary electron collector 237. The voltages shown are examples of voltages that might be used. The resistors 251 are load resistors and the resistor 252 is a current limiting resistor (for operation of circuit with this resistor see description of operation of circuit of Figure 9 above). The switches 253, 254 and 255 are arranged to apply to the input electrodes 228, 229 and 2'30 theeight'possible combinations of two voltages (approximately zero or +50 volts) with respect to the cathode 225, and each given combination of input voltages on the input electrodes causes current from the cathode to flow to a given output electrode. For example, if all the input electrodes have their negative voltage values (switches 253, 254 and 255 connected to ground), current will flow to output electrode 241 (see both Figures 1'8 and 19'). If all the input electrodes are positive (switches 253, 254 and 255 connected to +50 'volts), current will flow to output electrode 248. .For other combinations of positive and negative input voltages,

current wdl flow to one of the electrodes 242 to 247 inclusive.

Other types of switch tubes may be constructed according to-the invention and in some circuits it may be advantageous to combine the functions of two tubes according to the invention. For example, a 4 x 16 matrix can be formed from two 3 x 8 matrix tubes by connecting together the three input electrodes of each tube and also connecting together the secondary electron collector of each tube to form the fourth input electrode. Since each tube has eight output electrodes, there are sixteen output electrodes available. Similarly a 5 x 32 matrix can be formed from four 3 x 8 matrix tubes, the fifth input being taken to the cathodes of the tubes through a diode for each cathode. In each case the circuit would include current limiting means as described above, for example in "connection wi'th'Figures9 and .19.

An embodiment of a multiple electron beam tube according to the invention is shown in Figures 20 to 24 inclus'ive. The tube shown is a binary adder tube, but the other types of tubes described above can also be arranged for multiple beams. InFigures 2.0 to 24 the tube shown is a double beam one, but other. numbers of beams can be used, for example four beams as shown in Figures 25 to 29 inclusive. .Multiple beam constructions are advantageous in attaining a high speed of operation owing to their having a large ratio of output current to output capacity. .A multiple beam arrangement overcomes the shielding effects of the cathode and permits better focussing of larger currents. Figures 20 to 24 and Figures 25 to 29 correspond to Figures 3 to 8, and in Figures 20 to 29 the reference numerals are chosen so that the last two digits of each reference numeral are the same as that used for the corresponding part in Figures 3 to 8. As a result of this arrangement of the reference numerals, reference can be made to the description of Figures 3 to 8 for an understanding of the construction and operation of the tubes shown in Figures 20 to 29. It is to be noted that each input electrode in the tubes shown in Figures 20 to 29 has a plurality of component electrodes, each of which is designated by the reference numeral for the input electrode of which it is a component.

What I claim is:

1. In an electrical circuit for producing an output potential in response to a plurality of input potentials, a plurality of sources of input potential each of which has one of two values, a higher value or a lower value, each said source supplying said two values independently of the values supplied by the other source, an electronic vacuum tube comprising an electron-emissive cathode, a plurality of plate-like input electrodes facing said cathode and being spaced apart to provide a gap between the edges of adjacent input electrodes, an individual target electrode for each gap and situated to receive electrons flowing from said cathode through the corresponding gap only, individual input circuits connecting each input electrode to said cathode, means for applying a potential to the cathode, means for applying a positive potential to each target electrode with respect to the cathode, means for applying to each of the input circuits one of the said input potentials, means for deriving an output potential from each target electrode, and current-limiting means for limiting the current flow in said input circuits, the potentials applied to the cathode and to each target electrode being such in relation to the said predetermined values of input potentials that, if both the input potentials on two adjacent input electrodes have the said higher value, a beam of electrons will pass from the cathode through the gap between such electrodes to the target electrode associated therewith, while if at least one such input potential has the said lower value substantially no electrons will pass through the said gap.

2. A circuit as claimed in claim 1, for carrying out binary additions, wherein the tube comprises three input electrodes surrounding said cathode and each having an aperture, a set of target electrodes positioned respectively to receive electrons passing through the three gaps between the input electrodes, and a further set of target electrodes positioned respectively to receive electrons passing through the three apertures in the input electrodes, and the input potentials to the three input electrodes represent respectively an addend, an augend, and a carry digit.

3. A circuit as claimed in claim 1, for carrying out binary subtractions, wherein the tube comprises three input electrodes surrounding said cathode and each having an aperture, a set of target electrodes positioned respectively to receive electrons passing through the three aperapertured input electrodes surrounding said cathode and having two axial gapstherebetween, two non-apertured input electrodes situated. in one of the said gaps so that there is an axial gap between each non-apertured electrode and each apertured electrode and a circumferential gap between the non-apertured electrodes, a set of target electrodes positioned respectively to receive electrons passing through the several axial gaps, and a set of target electrodes positioned respectively to receive electrons passing through the circumferential gap and the axial gap between the apertured electrodes, and the input potentials to the apertured electrodes represent respectively a partial product digit and a carry digit, and the input potentials to the non-apertured electrodes represent multiplier and multiplicand digits respectively.

5. A circuit as claimed in claim 1, adapted to act as a 3 x 8 matrix, wherein the tube comprises a conoidal cathode, three conoidally arranged input electrodes surrounding said cathode and each having an aperture of generally triangular shape, an aperture deflecting electrode situated below the input electrode and exposed to the lowerpart of the cathode, six target electrodes positioned respectively to receive electrons passing through the apertures in and the gaps between the input electrodes, a target electrode situated above the central upper opening formed by the input electrodes, and a target electrode adapted to receive electrons passing through the apertures of the deflecting electrode, and the input potentials to the three input electrodes represent the required inputs to the matrix.

6. A circuit arranged to act as a matrix and comprising a plurality of circuits as claimed in claim 5 wherein each tube comprises a collector electrode situated between the input electrodes and the target electrodes and having apertures corresponding with the gaps between, and any apertures in, the input electrodes; and means are provided for maintaining the collector electrode at a potential of the same order as that :of each target electrode, and wherein means are provided for applying to the collector electrode of each tube a potential to control electron flow therethrough depending on the values of certain of the matrix inputs, the remainder of the matrix inputs being applied respectively to the input electrodes of the several tubes.

7. A circuit as claimed in claim 1, wherein the tube comprises a collector electrode situated between the input electrodes and the target electrodes and having apertures corresponding with the gaps between, and any apertures in, the input electrodes; and means are provided for maintaining the collector electrode at a potential of the same order as that of each target electrode.

8. A circuit as claimed in claim 1 in which the currentlimiting means is connected in series with the cathode of the tube.

9. A circuit as claimed in claim 1 in which the currentlimiting means comprises a resistor connected in series with each input electrode of the tube.

10. A tube comprising a conoidal cathode, three conoidally arranged input electrodes surrounding said cathode with gaps between adjacent electrodes and each having an aperture of generally triangular shape, an apertured deflecting electrode situated below the input electrodes and exposed to the lower part of the cathode, six target electrodes positioned respectively to receive electrons passing through the apertures in and the gaps between the input electrodes, a target electrode situated above he central upper opening formed by the input electrodes, and a target electrode positioned to receive electrons passing through the apertures of the deflecting electrode.

11. A tube as claimed in claim 10 comprising a conoidal collector electrode situated between the input electrodes and the target electrodes and having apertures corresponding with the gaps between the input electrodes.

12. A tube comprising a central cylindrical cathode, four input electrodes in the form of plates cylindrically 15 arranged about the cathode with the axis of the cathode as centre, each of two of the input electrodes having an aperture facing the cathode and being spaced apart by gaps facing the cathode, one of said gaps being wider than the other and containing the other two input electrodes, said other two input electrodes being Spaced apart by a gap in a direction parallel to the axis of the cathode, an interconnected set of target electrodes positioned to receive electrons from the cathode passing through each said aperture and through said gap between said other two input electrodes, and an interconnected set of target electrodes positioned :to receive electrons from the cathode passing through the narrower one of said gaps by which said input electrodes having apertures are spaced apart and passing through said gap between said other two electrodes.

13. A tube comprising a cathode, three input electrodes surrounding said cathode and having three gaps therebetween, each input electrode having an aperture therein, a set of target electrodes positioned-respectively to receive electrons passing through said three :gaps and having a common terminal, and a further set of target electrodes positioned respectively to receive electrons passm through the three apertures in the input electrodes and having a common terminal insulated from thecommon terminal of said first set of target electrodes, and a cylindrical collector electrode situated between the input electrodes and the target electrodes and having apertures corresponding with the gaps between and the apertures in the input electrodes.

References Cited in the file of this patent UNITED STATES PATENTS 

